The present invention relates to vehicles incorporating computer controlled suspension operation, electrically driven wheels, and configurations for amphibious operation. In particular, the present invention relates to rapid deployment vehicles, such as military vehicles. The present invention also relates to non-military vehicles (e.g., civilian vehicles, SUVs, aircraft recovery vehicles, fire fighting vehicles, agricultural vehicles, forestry vehicles, etc.).
In its battlefield or support role, a modern military vehicle is often expected to have high level of mobility (e.g., the ability to rapidly traverse a wide range of difficult terrain). In many cases, battles are won or lost on the effectiveness of military vehicle mobility in both fighting vehicles and associated logistics vehicles.
There are many conventional design requirements needed to achieve a given level of vehicle mobility. Substantially comprehensive mobility analysis can be conducted (e.g., during the design phases of the vehicle) by computer programs such as the NATO Reference Mobility Model (NRMM) and dynamic modeling software (e.g., DADS, ADAMS, etc.). Despite these types of programs, the actual mobility levels of wheeled military vehicles in service around the world have not increased dramatically for many years.
In recent years, there have been many changes in the world that have influenced both the nature of the battlefront and the needs of military forces. Various recognized logistical problems in the rapid deployment of heavily armored vehicles such as tanks overseas have had an impact on the traditional heavy armored approach to battle warfare, sometimes in favor of lighter, air-transportable vehicles. For this type of approach, it is useful to have vehicles that are difficult for an enemy to locate and that incorporate high levels of stealth (e.g., the capability to deny the enemy the ability to locate or target a vehicle).
The availability of a portfolio of stealth measures along with advances in communication, information technologies, and smart remotely deployable armor-piercing weaponry brings into focus the possibility of fielding a hidden stealth force (e.g., a disseminated force of smart-weapons-equipped, highly mobile stealth vehicles, capable of outrunning, out-maneuvering and destroying a tank force). A stealth force is useful because it is air transportable and deployable. The stealth force is deployable almost anywhere in the world within hours, rather than the weeks or months often needed for the deployment of some conventional tank forces. However, in order to perform their functions from a distance, it is advantageous for these more lightly armored wheeled vehicles and their supply lines to have the capacity to outrun and out-maneuver contemporary battlefield vehicles.
The differences in the nature of the mobility of tracked versus wheeled vehicles is a consideration when determining features of a stealth force. For example, a tank can force its way through fairly dense vegetation and/or covered terrain that may be inaccessible to lighter wheeled vehicles. Accordingly, in order to meet the objectives of remote stealth operations, it is advantageous to improve mobility over rough terrain as well as dense and covered terrain.
The advent of new “enabling technologies” such as active suspension, drive by wire or light (DWL), advanced lightweight materials, new drive systems, etc. may not, by themselves, be sufficient to achieve the desired level of mobility in future rapid deployment stealth vehicles. This is because of the limitations imposed by transportability considerations. For example, despite these technologies, it is still necessary to transport a vehicle to its place of deployment. This dictates many aspects of the vehicle's design, and can inhibit many desirable attributes needed for mobility.
In many cases, transportation may be done under the vehicle's own locomotion along normal highways, or more commonly by rail, sea-born or aerial transport (e.g., C130 limits). Accordingly, the criteria for highway operation is similar to civilian vehicles—the vehicle should conform to maximum individual axle and gross vehicle weight loadings appropriate for the highway systems and bridge structures it may be driven over. Overall height should be such that it can safely pass under bridges and through road tunnels etc., while its maximum length, width and turning circle should be appropriate for the road systems over which it may be used. Effectively, this means that a military vehicle, in some instances, should conform as much as possible to highway regulations, not only in its country of origin, but in all countries that it may be used.
In addition, rail and sea transportation can impose dimensional conditions on military vehicle design, with rail-tunnel clearance imposing strict width and height disciplines, which vary from continent to continent. Ships, especially roll-on/roll-off ferries, can also define allowable heights and widths.
For rapid deployment military vehicles, an important transportation capability is air transport. However, air transportation by heavy transport aircraft imposes not only dimensional constraints on height, width and length, but also places limits on overall weight, individual axle weights, and also defines, how the axles share the load during the loading/unloading operation. Air transport by helicopter is oftentimes weight dependent. The vehicle should be within the allowable lift capacity of the helicopter to be transported (a lesser weight extending the lift range and ceiling height limits). Because getting the vehicle to its place of deployment is in most cases a pre-condition to deployment itself, compliance with each of the forgoing criteria will normally limit the potential design of the vehicle for its battlefield or support role.
Achieving the necessary length of vertical suspension travel in jounce and rebound for certain levels of mobility is useful in designing fast, highly mobile, off-road wheeled vehicles. The practical advantages of long suspension travel for high-speed operation over rough terrain have been demonstrated by vehicles competing in competitive off-road racing events, where suspension travel as great as 30 inches full jounce to full rebound is sometimes utilized.
Specially designed tires are often used for off-road operation in conventional systems and vehicles. The tire size can effect off-road mobility. Larger diameter tires are typically better for off-road situations except under certain circumstances such as when the mass of the tire itself becomes the limiting factor by reason of inertial and hysteresis effects. With current tire technology and vehicle operating speeds, the practical advantages associated with increased tire size are oftentimes not lost until the diameter reaches about 60 inches or more.
The maximum allowable tire diameter is typically considered together with the maximum allowable suspension jounce travel, another parameter which can effect vehicle off-road mobility. The limit of allowable rear suspension vertical or jounce travel is set by the bottom or support structure of the containerized load. The height position is set by the height of the top of the container and the under-bridge clearance requirements. A compromise is typically determined using computer simulations of vehicle operation over the desired terrains in the appropriate weather conditions.
In addition to compromises between wheel diameter and suspension jounce travel due to the maximum permissible overall height of the vehicle, a similar limitation can also apply to other types of military vehicles having a lower overall height. For example, the center of gravity of a vehicle can be a limitation. At a maximum permitted off-road payload, increasing the rear suspension jounce by raising the vehicle's cargo-bed may improve mobility over some terrains, but may decrease mobility over other terrains by virtue of its increased propensity to roll-over due to the increased center of gravity height. Some military vehicles that meet the above-described transportability requirements provide a balanced compromise between a number of potentially conflicting parameters in order to realize the comparatively high level of mobility that has conventionally been needed. This has been accomplished at least in part due to the experiences of operation influencing vehicle design as well as the ability to simulate vehicle dynamic behavior using computer modeling. Despite these compromises, mobility can still be improved.
The successful achievement of long suspension travel is not oftentimes straightforward, even on vehicles where the primary function is dedicated to off-road racing. The design compromises typically made to the length of suspension travel for vehicles that require a high level of off-road mobility, but whose function also incorporates design features for meeting a range of additional requirements, can be challenging. Such vehicles include SUVs and pick-up trucks, which additionally need to meet the practical and legislative requirements of highway operation, as well as wheeled military vehicles that also meet a variety of additional specialist functions.
If enough clearance is provided with conventional vehicles to permit the use of wheels and tires large enough and suspension vertical travel long enough to give the needed high levels of mobility, for example, by moving the wheels laterally outwards beyond the body width of the vehicle to achieve the necessary space, there still are a number of other potential problems that are to be addressed. One such problem relates to the types of suspension linkages suitable for the application and that can support a long vertical suspension travel (e.g., perhaps as great as one wheel diameter of about 50 inches).
There are various advantages and disadvantages of conventional double A-arm, or lateral control arm, independent suspension for off-road operation. Because the suspension system pivotal axes are essentially in line with the vehicle's longitudinal axis (depending on the detail of design) there is often little, if any, sensitivity to wheel torque reaction. That is, if braking or drive torque were to be reacted into the outboard ends of the control arms this, in itself, would not result in the generation of significant spurious vertical forces causing the vehicle's sprung mass to be raised or lowered at that axle position. However, the effective roll center of a double A-arm suspension is quite low, sometimes below ground surface level, so the vertical moment distance to the vehicle's sprung mass center of gravity is greater than for other suspension systems, resulting in a propensity to body roll when reacting to lateral forces such as in cornering or side slope operation. Further, the limited length of the A-arms, which “eat” into the useable chassis or body width, can limit the suspension travel. Accordingly, such systems are often not good. candidates for use where long suspension travel is required. Solid axles, which are commonly used on medium and heavy trucks, and which comprise a single axle housing an integral differential and spanning the inside width between wheel pairs, are typically limited with respect to vertical jounce travel by potential contact with the vehicle's chassis rails or underside of the cargo bed or power source.
Leading and trailing-arm suspension systems are relevant to the design of off-road vehicles because they can achieve the necessary length of wheel travel without “eating into” the width of the vehicle's hull or understructure as compared to more conventional lateral control arm suspension designs. Trailing or leading link suspensions are utilized for some off-road operation including tanks and other tracked vehicles. Tank tracks are typically sprocket-driven from a fixed (unsprung) axle-drive, while the leading and/or trailing arm support wheels, which bear the tank's weight along the track length, are not driven. In the case of a wheel-driven vehicle using trailing and/or leading-arm suspension, consideration is given to containment or elimination of both the effects of drive and brake torque reactions, as well as moments generated about the suspension pivotal axes by the longitudinal drive thrust and braking forces. Such reactions are capable of generating spurious vertical force components, which may be detrimental to suitable operation of the suspension system, especially with respect to Near Constant Force (NCF) springing.
For highway operation where the extent of vertical suspension travel is generally modest in comparison to off-road needs, problems can occur when driven axles are combined with leading or, more commonly, trailing arm suspension systems. The generation of spurious vertical forces is sometimes pronounced when wheel torque and/or tractive force is high, such as for commercial trucks. The dynamic interaction between wheel torque reaction or tractive force and spurious force can be problematic, giving rise to wheel hop and transmission judder. In the case of the trucking industry, the phenomenon is often prevalent and is known as “frame rise.” Frame rise is often attributed to the reaction of axle reaction torque into the suspension trailing arms.
Axle torque reaction causes frame rise when the trailing arm is aligned with the vehicle's horizontal axis. When the trailing arm is at an angle θ to the truck's horizontal axis, a vertical force component Vf=tan (θ)×Tf, where Tf is the tractive force of the axle or wheel. Therefore, if a trailing arm were, for example, at a 45 degree downward inclination from the truck's horizontal axis, the magnitude of the spurious vertical force generated at the trailing arm's attachment to the truck's frame would equal the horizontal tractive thrust component at the same point to propel the truck. This can limit the application of leading and trailing arm linkages for long suspension travel applications.
The packaging space to achieve the desired length of suspension travel and wheel diameter as well as the type of suspension linkages used are not the only factors to be taken into consideration when analyzing vehicle mobility or total vehicle design for future wheeled military vehicle operation.
For mobility, there are a number of other design considerations, each of which, if not correctly addressed with the appropriate weighting in a balanced vehicle design, can limit a vehicle's mobility, despite good design practice in other areas. One way to identify these parameters and to quantify their influence over different types of terrain in various weather conditions is to study the NRMM source code and manuals, and/or to run NRMM simulations. Of course, as one skilled in the art would appreciate, other methods may also be used.
In addition to the wheel/tire diameter and length of vertical suspension travel already mentioned, some other exemplary vehicle related parameters include vehicle weight, individual wheel/axle load at the ground, number of wheels/axles, number of driven/braked wheels/axles, tire characteristics/tire pressures, available locomotive power, transmission characteristics and efficiencies, tractive force, underbody ground clearances, front pushbar strength and height, driver's forward view (vision height above ground), braking capability, vehicle/suspension dynamics, lateral stability, steering/maneuvering capability, fording/amphibious capability, etc.
In addition to mobility related features and the ability to be transportable by road, rail air and sea, there are a number of other desirable features that future highly mobile response vehicles may incorporate. For example, lightweight construction is a desirable feature for the transportation of rapid deployment vehicles by C130 transport aircraft and/or for helicopter lift. It is also a beneficial feature for mobility and for vehicle fuel efficiency.
Physical aspects which, when advantageously addressed, are likely to provide a lighter vehicle weight include designs allowing stresses to pass through outermost fibers, maximized separation of outermost fibers, use of shape and shaping advantageously, triangulations rather than cantilevers, use of lightweight materials, use of containers, flatracks or cargo beds as stressed parts of the structure, use of armor/landmine protection as stressed parts of the structure, identification and use of light reliable discrete components, avoidance of stress raisers or fatigue prone jointing methods, and avoidance of both weight and cost by eliminating unnecessary components. In order to deny an enemy the ability to readily target the vehicle, visual, radar, thermal, and acoustic signatures may be minimized. In addition, it may be desirable for the vehicle to be able to “kneel down” by reducing its suspension height, such that it can align its cargo deck with the cargo deck of a C130 or other transport aircraft to facilitate fast unloading and loading of containerized and flatrack mounted cargos.
It is desirable for the vehicle to protect its occupants and critical systems against Nuclear, Biological and Chemical (NBC) weapons attack as well as Electro-Magnetic Pulse effects. EMP hardening is one aspect of design that is desirable for stealth , operation. This is because any EMP vulnerability is the one way that an enemy may be able to collectively neutralize an entire vehicular force without first having to precisely locate them. EMP weapons include nuclear devices but also a range of possible advanced electromagnetic weapons as well as so called E-bombs such as Flux Compression Generators (FCGs) which use conventional explosive and electrical systems, and which have the potential to be manufactured with limited technical capability. It is desirable for the vehicle and its discrete electronic and communication systems to be protected from Electro-Magnetic Interference (EMI), whether from external sources or its own internal systems or on-board weapons such as directed energy weapons. In addition, it is desirable for the vehicle to be able to protect its occupants and critical systems against light weapons fire and mine blast. It is also desirable for the vehicle to be able to ford a significant depth of water (typically 60 inches).
In view of the foregoing, it would be desirable to provide a highly mobile and maneuverable vehicle incorporating a leading or trailing arm suspension system compensated against torque and spurious vertical force reactions, and which could adapt its wheel-track, suspension geometry, and cab height from its on-road, air, rail, or sea transportability modes to a wide track and long suspension travel configuration. This would allow the wheels to move up past the vehicle's sides in order to overcome the limitation of suspension movement caused by the presence of the body or cargo-bed. It would be desirable to provide a system having long off-road suspension with movements of up to about 50 inches or more, thereby enabling reduced vertical accelerations on the vehicle, occupants and cargo, while traversing severe terrain at high speeds difficult for vehicles with conventional shorter travel suspension systems.
It would further be desirable to provide a vehicle that has the ability to be lowered between laterally extended wheels when needed. This configuration is advantageous for several reasons including a reduction in detectability and vulnerability to attack, the lowering of the center of gravity for improved stability, the grounding of the vehicle to allow heavy recoil weapons, the ability for personnel carried within an armored personnel carrier module to embark and disembark close to ground level, the ability to reduce cargo bed height to align exactly with transport aircraft decks, and readily permit fast, automated cargo transfer to and from an aircraft.
It would further be desirable to provide a vehicle having the capability to lift one or more wheels from the ground to minimize tire drag and/or improve fuel efficiency when carrying less than a full payload and/or to allow the vehicle to proceed in the event that a wheel or tire suffers damage. It would also be desirable if the operation of the vertical height and vertical movement of one or more wheels is manipulated as needed to cross obstacles such as steps, walls or trenches. It would further be desirable to configure the vehicle so that the wheel drive torque of the vehicle could be varied from one side to the other as required in order to effect differential torque steering or “skid steer” to steer the vehicle or to augment conventional or Drive by Wire or light (DWL) steering.
It would further be desirable to provide a vehicle that incorporates DWL technology having electrically driven wheels, and/or be of modular “plug and play” construction permitting multiple vehicle configurations for varied purposes to be assembled from a limited range of common modules, with the reconfiguration of module function primarily by software changes to the vehicle's management and/or control protocols. This enables combined driven, steerable and actively suspended axle modules complete with central tire inflation (CTI) systems to be integrated with cargo supporting and handling modules, power source and cooling modules, cab modules etc., and arranged in different vehicular layouts. For example, 4×4, 6×6, 8×8, 10×10 and/or other vehicle configurations may be built as needed, or even reconfigured by the end user according to future needs as they arise. Additionally, such high-level modularity provides a convenient means to break a larger (8×8 or 10×10) vehicle down into multiple segments for helicopter lift purposes.
It is preferable for the same plug and play modularity and protocols to be used for powered and unpowered trailers, articulated vehicles, autonomously operated vehicles and “mobility platforms” useable for a variety of vehicles including both logistics, scouting and fighting vehicles.
Modularity results in a benefit of achieving commonality and interchangeability of components and modular parts across a fleet. Not only does it reduce the number of replacement parts, either carried on the mission or available for air-drop, it improves the sacrificial value of any immobilized vehicles while serving to reduce the cost of manufacture by virtue of economy of scale. Further, it serves to reduce the level of personnel training, tools required, and costs to service and maintain a fleet.
It would further be desirable to provide a vehicle that incorporates the appropriate design and management of cooling flows, both ventilated (NBC contaminatable) for primary cooling, and refrigerated or conditioned for non-contaminatable areas such as for NBC protected personnel areas and areas housing equipment such as open electronic systems that are typically unsuited to normal decontamination procedures. It would also be desirable to provide a vehicle that is furnished with a suspension system of the Near Constant Force type so that rough terrain has minimal disturbance on the primary mass of the vehicle.
It would also be desirable to provide a suspension that is controlled by a device and/or system that actively controls the ride height and pitch and roll attitude, preferably deriving vehicle primary mass corrective forces from energy captured from the natural process of traversing the undulating terrain, rather than from extracting energy from the vehicle's power source and thus potentially degrading fuel efficiency.
It would also be desirable to provide the natural frequencies of the unsprung masses of the wheels, tires, and suspension systems to be dampened by a method which at least minimizes corrective forces between the unsprung masses and the vehicle primary mass, thereby reducing spurious force inputs into the primary mass while reducing suspension scanning and corrective frequencies.
It would be desirable to provide a vehicle that is furnished with a cab module that is readily demountable and interchangeable, and has the ability for the cab height to be adjustable in operation. It would be desirable to configure the vehicle cab to be mounted on the front of the vehicle on a height adjustable but common interface with other vehicles in a class. This enables cab types to be interchangeable without tools or forklift equipment, so that cabs may be provided and used in a number of different forms appropriate for the vehicle's intended usage.
There are several types and degrees of armor and mine-blast protection. Less armored cabs can be more spacious and can be furnished with more glass area to offer better general driver visibility at less cost. In addition, less armored cabs typically have a less intimidating appearance to the populous and can be used for domestic or non-hostile operations. Further, special purpose cabs may be provided for use with particular weapons or equipment modules, or for amphibious operation.
Having the cab set low for transportation purposes improves the reduction of visual and radar signatures. For high speeds over rough terrain, it is useful to mount a cab higher for improved forward visibility. For displacement amphibious operation the cab represents a buoyant element and the shaped forward portion of the vehicle's bow. Therefore, to improve buoyancy and lower hydrodynamic drag, the undersurfaces of the cab are aligned with the undersurfaces of the vehicle's main lower-hull. For planing amphibious operation, the design lower surfaces of the cab which form the bow of the vehicle can have a bearing on the vehicle's planing power requirement and wave height capability. Accordingly, it would be desirable to configure the undersurface of the cab to be aligned marginally below the undersurface of the main lower-hull to form a planing step.
In view of various problems discussed above, it would be desirable to provide a leading and/or trailing arm suspension linkage for driven axles of off-road vehicles, capable of large vertical displacement without generating significant spurious vertical forces as a result of vehicle tractive thrust. In addition, it would be desirable to provide a shorter suspension travel for highway vehicles.
In view of various problems discussed above, it would be desirable to provide a highly mobile and maneuverable vehicle which adapts its wheel-track, suspension geometry, and cab height from its on-road, air, rail, or sea transportability modes to a wide track and long suspension travel configuration to enable high speed mobility over difficult cross-country terrain. In addition, it would be desirable to provide a rapid deployment vehicle incorporating computer controlled suspension operation and electrically driven wheels, and/or those used for amphibious operation.
It would be advantageous to provide a system or the like of a type disclosed in the present application that provides any one or more of these or other advantageous features. The present invention further relates to various features and combinations of features shown and described in the disclosed embodiments. Other ways in which the objects and features of the disclosed embodiments are accomplished will be described in the following specification or will become apparent to those skilled in the art after they have read this specification. Such other ways are deemed to fall within the scope of the disclosed embodiments if they fall within the scope of the claims which follow.